Auto Electronics: 2002 Ford Taurus electrical problem, ford taurus, problem surfaces

Question
I have a 2002 Ford Taurus and lately I have been experiencing some electrical problems. A few months ago I have to replace the blend door actuator. Then about a month after I noticed issues with the dash lights and the radio. I would hit a bump, both turn signal lights would come on and stay on. At night when that happened the instrument cluster lights got really dim to a point of being dark.
THe next instance it happened I lost everything, no dash lights and the speed and Tach dropped to zero. I gently tapped on the side of the dash by the radio and everything returned to normal.
Next instance the ac stopped working, the blower motor must of turned off but I still heard a whining noise like it was working.

I took the radio out again when this happened and jiggled the wire harness that runs into the radio. When I pulled the wire up everything worked right. But as soon as I let go and it dropped back down things stopped.

Does that harness need to be grounded to the frame of the dash or does it need to the hooked up to something to keep it from hanging?

Any opinion would help.Thanks

Answer
Sounds to me like a short has been created in that area, although it is still possible that a lack of ground is the reason for your problems, the good news is that it seems that you have narrow it down to a very specific area of the harness (directly behind the radio), you need to perform a good detective work by stripping down the wiring on that area, hold, twist, tap and wiggle until the problem surfaces right in front of your eyes. Good luck.